Currently, industrial countries generate most of their electricity in centralized utility power facilities, such as fossil fuel, nuclear, large solar power, or hydroelectric power plants. These centralized facilities usually transmit electricity over long distances to supply power to residences and businesses. Distributed energy generation is a recent innovation in which distributed energy resource (DER) systems are located very near where the energy is to be consumed, and typically entirely replace, or at least supplement, power supplied by the centralized utility power system. DER systems typically include small scale power generators that may supply power to one or more local residences and/or businesses. The close proximity of the DER systems to the energy consumer(s) reduces the amount of energy lost in transmitting electricity, and also reduces the size and number of power lines that must be constructed in the utility power system. DER systems may, in some instances, use renewable energy sources such as, for example, sunlight, wind and geothermal sources. The availability of cheap natural gas has also fueled the adoption of distributed energy generation using natural gas.